1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to an electronic signature, and more particularly, to generating an electronic signature, which can be verified in a shorter time, and a computer readable recording medium including a computer program for executing the method.
2. Description of the Related Art
To prevent illegal modification of software data stored in a user device, it needs to be verified whether the software data is identical to the original copy. Illegal modification of software data may occur in various situations, such as hacking copyright-protected content, etc.
It is assumed that particular applications allow playback of content only if the content is proven to be valid by verifying an electronic signature of the content. In this case, a hacker may attempt to modify a validity verifying module of the application so as to allow the playback of invalid content.
Therefore, when the application is modified, the application should not play back content protected by a digital right management (DRM) technology. An example of DRM technology for ensuring that an application does not play back content when the application is modified is an advanced access content system (AACS).
An electronic signature is the most commonly used method for verifying illegal modification of software data. In other words, software data and an electronic signature corresponding to the software data are stored in a user device together. When the user device operates, it is decided whether to execute the software data or not based on a result of verifying the electronic signature.
Verifying an electronic signature is advantageous in terms of verifying illegal modification of software data such as firmware. However, it may take an extended period of time to verify an electronic signature according to performance of a user device, and thus it is necessary to reduce the time required to verify an electronic signature while maintaining the advantages of an electronic signature system.